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Se analiza la estratigrafía y el contenido de microfósiles para evaluar la sucesión de eventos entre una estructura residencial temprana y las estructuras agrícolas adyacentes de la Mesada del Agua Salada (valle de Yocavil, provincia de Catamarca). En el recinto se registraron tres unidades estratigráficas: 1) relleno de nivelación antrópico, 2) nivel de ocupación, y 3) relleno posdepositacional reciente. El perfil de las estructuras agrícolas refleja dos ciclos: uno superior (A), que se dispone sobre un ciclo inferior de horizontes Ab-A/Cb-Cb. El análisis de las asociaciones de microrrestos y de los procesos de formación de cada perfil permite establecer una secuencia de cinco eventos y una correlación entre el piso de ocupación y el material parental del paleosuelo. Se concluye que la ocupación de la unidad residencial es anterior a la construcción y utilización de las estructuras agrícolas. In this paper, the stratigraphy and content of microfossils are analyzed to evaluate the succession of events relating an early residential structure and the adjacent agricultural structures of the Mesada del Agua Salada, Yocavil valley, Catamarca province. Three stratigraphic units were recorded at the site: 1) anthropic leveling fill; 2) an occupation level; and 3) recent post-deposition fill. The profile of agricultural structures reflects two cycles: an upper one (A), and a lower cycle of horizons, Ab-A/Cb-Cb. The analysis of microfossil associations and formation processes of each profile enabled a sequence of five events to be established and a correlation made between the occupation floor and the parental material of the paleosol. It is concluded that the occupation of the residential unit predates the construction and use of the agricultural structures.

The middle and upper parts of the lower Miocene Santa Cruz Formation (~17–15.9 Ma) in the southeastern Austral-Magallanes Basin (southern Patagonia, Argentina) crop out as a fluvial succession that in parts is pedogenically modified. The study of the paleosols of this unit combined with the study of ichnofossils, microremains, and fossil vertebrates present in these allows us to reconstruct past environmental, ecological, and climatic conditions, as well as paleolandscape evolution of the Santa Cruz Formation during ~1 my. These reconstructions demonstrate three different stages during which very weak to moderate pedogenesis took place. The first one (middle part of the unit) is an epiclastic distal floodplain bearing Calcisols or paleo-calcic Inceptisols, which record a relatively dense vegetation integrating trees, shrubs, palms, and short grasses. Soil fauna is scarce and it is in association with a vertebrate fauna typical of coastal “Santacrucian assemblages”. The second landscape stage (the bottom of the lowermost upper part of the unit) is composed of epiclastic distal floodplain areas and minor pyroclastic proximal floodplain settings that contain mainly Vertisols. Vertisols record an ecosystem dominated by grasses and palms adapted to variable conditions in hydric availability (C4 plants) and by solitary bee larvae, and adult and nymph soil beetles. Finally, up-section, the third stage attests to the existence of an epiclastic and pyroclastic distal and proximal floodplain over which Protosols developed. Past ecosystems supported grass vegetation (C3 plants), oligochaete annelids and a moderately diverse insect soil fauna (interpreted by their trace fossils) composed of solitary bee larvae, soil beetles and their pupae, cicada nymphs, and myriapods. This combined abiotic (paleosols) and biotic (ichnofossils, microremains, and vertebrates) study indicates that several factors controlled the landscape evolution during the early Miocene of southeastern Patagonia. Highly aggrading fluvial conditions, variations in the position in the floodplain and in sedimentation/pedogenesis ratio, the input of pyroclastic materials, the length of landscape stability, changing hydrologic conditions, and fluctuations of wetter and drier phases in a context of relatively warm and humid climate, seem to be the main factors controlling the landscape, Centro de Investigaciones Geológicas, Facultad de Ciencias Naturales y Museo

Se analizaron los contenidos de microrrestos de tres terrazas agrícolas del primer milenio A.D. del valle de Ambato (Andes del sur, Catamarca, Argentina). Con el fin de determinar si estos elementos pueden contribuir a la caracterización de estas terrazas, se contabilizó la presencia de granos de almidón, estomatocistes de chrysostomatáceas, espículas de esponjas, diatomeas, microcarbones, esporomorfos y fitolitos. Los resultados, con énfasis en el detalle de la presencia de fitolitos y granos de almidón, permitieron establecer tendencias de composición que distinguen a las asociaciones compuestas por gramíneas cultivadas y silvestres/ruderales, y posibilitaron estimar la presencia de cultivos que no producen fitolitos. Los análisis de las pedosecuencias mostraron en muchos casos una mezcla composicional que no permitía establecer niveles diferenciales entre las asociaciones de un mismo perfil., Microremains of three agricultural terraces from the first millennium A.D. in the Ambato Valley (Southern Andes, Catamarca, Argentina) were analyzed. Starch grains, stomatocysts of chrysostomataceae, sponge spicules, diatoms, microcharcoals, sporomorphs and phytoliths were counted in order to determine whether these elements could help to the characterization of these terraces. The results, with emphasis on the detail of phytoliths and starch grains, allowed establishing compositional trends that distinguish the contribution of cultivated and wild/ruderal grasses and the possibility of the presence of crops that do not produce phytoliths. The analyzed pedosequences showed blend microremain compositions in many cases that did not permit to establish differential levels between associations of the same profile., Sociedad Argentina de Antropología

Este trabajo presenta las características de los registros arqueológicos de dos sitios recientemente retomados, denominados Alero El Mirador y Abrigo La Grieta. Se dan a conocer los resultados del análisis de los conjuntos líticos, del registro zooarqueológico y paleoambiental (obtenidos a partir de la evidencias de diatomeas, antracología y fitolitos), y su relación con las unidades estratigráficas. Esta información proxy permite hipotetizar aspectos del manejo antrópico de recursos naturales locales y de eventos paleoclimáticos ocurridos en el sector serrano de Tandilia oriental durante distintos tramos de la secuencia Pleistoceno-Holoceno., This paper presents the characteristics of the archaeological record of two sites recently taken up, called Alero El Mirador and Abrigo La Grieta. The study of different proxy data like lithic assemblages, zooarchaeological and paleoenvironmental record (obtained by diatoms, phytoliths and anthracology inferences) and their relationship to stratigraphic units, allows us to hypothesize anthropic management aspects of local natural resources and paleoclimatic events occurred in the eastern of Tandilia hill during different moments of the Pleistocene-Holocene archaeological sequence., Facultad de Ciencias Naturales y Museo

The phytolith morphology belonging to the leaves of 8 species of Stipa (S. brachychaeta Godr., S. charruana Arechav., S. filiculmis Delile, S. hyalina Nees, S. neesiana Trin. et Rupr., S. papposa Nees, S. philippii Steud. and S. trichotoma Nees), present in the prairies of Entre Ríos Province, is described. A new terminology and descriptive methodology to define the phytolith assemblage of each species is used. Cluster analysis (UPGMA) and principal component analysis (PCA) were performed on the data of 49 morphological characters from the 8 phytolith assemblages (OTUs). The results define three groups, the first group inelude S. filiculmis and S. trichotoma assemblages, the second one with S. hyalina and S. neesiana assemblages and the third one with (S. brachychaeta + S. charruana) + (S. papposa + S. philippii) assemblages. The 8 phytolith assemblages show Arundinoideae affinity (sensu Twiss, 1992), and differ from the typical phytolith assemblages of other Poaceae subfamilies., Facultad de Ciencias Naturales y Museo

El análisis de los fitolitos es una de las disciplinas paleobotánicas utilizadas para la reconstrucción de ecosistemas pasados ya que proporcionan un registro preciso de una parte de la vegetación, en áreas concretas y en un momento determinado. Un fitolito es una biomineralización de origen vegetal, de composición principalmente silícea (sílice amorfa) y tamaño microscópico, que puede ser hallado formando parte de un tejido vegetal, o bien en forma desagregada del mismo. Al ser los fitolitos microrestos resistentes, con buen grado de especificidad, constituyen una importante herramienta para estudios taxonómicos y de diversidad biológica en el pasado, ya que ciertas formas son diagnósticas de determinados grupos vegetales. Teniendo en cuenta la importancia de estos análisis se estudió la composición y variabilidad fitolítica de los sedimentos loéssicos cuaternarios de la Formación Tezanos Pinto en el sudoeste de la provincia de Entre Ríos. Los datos de base obtenidos permitieron caracterizar la paleocomunidad existente al momento de depositación de los sedimentos loéssicos, e interpretar las condiciones paleoambientales imperantes en el sudoeste de Entre Ríos durante el lapso Pleistoceno Tardío-Holoceno Temprano., Phytolith analysis is one of the paleobotanic disciplines used for the reconstruction of past ecosystems, because they provide a precise record of part of the vegetation for a specific time and place. Phytoliths are biomineralizations generated by plants; they are microscopic and mostly siliceous in composition (amorphous silica), and can be found within plant tissues or disaggregated. Because phytoliths are resistant and highly specific microremains, they represent an important tool for studies of taxonomy and biological diversity in the past, since some forms are diagnostic for certain plant groups. In this context, the composition and variability of phytoliths in Quaternary loessic sediments from the Tezanos Pinto Formation in southwestern Entre Ríos province. The data obtained allowed characterizing the paleocommunity that existed at the time when the loessic sediments were deposited, and interpreting the paleoenvironmental conditions that prevailed in southwestern Entre Ríos during the Late Pleistocene-Early Holocene lapse., Facultad de Ciencias Naturales y Museo